Clamping holder for a cutting tool

ABSTRACT

A clamping holder comprising an elongated groove of dove-tailed cross-section for lengthwise accommodation of the square steel bar of a cutting tool to be clamped therein, and comprising a wedge-like liner of U-shaped cross-section placed with transversal play in the groove and adapted to embrace the tool bar on three longitudinal sides and pressing screws screwed in the liner for engaging the middle side among the embraced sides of the tool bar and urging the latter with its opposite longitudinal side into clamping engagement with the base surface of the groove, whereby the wedge-like flanks of the liner are adapted to press upon the two other longitudinal sides of the tool bar.

United States Patent [1 91 [111 3,811,162 Bay May 21, 1974 54] CLAMPING HOLDER FORA cu'mm; 2,855,658 10/1958 Garih 2 9/105 TOOL Inventor: Otto Bay, Luzernstrasse 351,

CH-4553 Subingen, Switzerland Filed: Mar. 14, 1972 Appl. N0.: 234,569

Foreign Application Priority Data Mar. 16, 1971 Switzerland 3847/71 US. Cl. 29/96 Int. Cl B26d l/02 Field of Search 82/36, 37; 85/74, 75;

References Cited UNITED STATES PATENTS 10/1970 Mueller ..29/96 3/1970 Williams .,29/96 Primary Examiner-Andrew R. .luhasz Assistant Examiner-W. R. Briggs Attorney, Agent, or Firm-Michael S. Striker the groove and adapted to embrace the tool bar on three longitudinal sides and pressing screws screwed in the liner for engaging the middle side among the embraced sides of the tool bar and urging the latter with its opposite longitudinal side into clamping engagement with the base surface of the groove, whereby the wedge-like flanks of the liner are adapted to press upon the two other longitudinal sides of the tool bar.

1 Claim, 3 Drawing Figures BACKGROUND OF THE INVENTION With hitherto known clamping holders for fastening a cutting tool on its square bar in working position, the bar is clamped only on two opposite longitudinal sides. This tool clamping can be insufficient, particularly with high cutting stresses and for precision cutting. It is the main object of the invention to provide a cutting tool holder wherein the pressing screws located on one longitudinal side with respect to the tool bar are adapted to cause a clamping effect of the holder upon all four sides of the tool bar.

SUMMARY According to the present invention there is provided a clamping holder comprising an elongated groove of dovetailed cross-section for lengthwise accommodation of the square steel bar of a cutting tool to be clamped therein, and comprising a wedge-like liner of U-shaped cross-section placed with transversal play in the groove and adapted to embrace the tool bar on three longitudinal sides, the liner having on its flanks outer wedge surfaces on opposite sides longitudinally to the groove and a middle wall connecting the flanks and being located near the longitudinal opening of the groove, the middle wall being traversed by pressing screws screwed therein for engaging the middle side of the embraced sides of the tool bar and urging the latter with its opposite longitudinal side into clamping engagement with the base surface of the groove, whereby the flanks of the liner are adapted to press upon the two other longitudinal sides of the tool bar.

In a preferred embodiment of the invention one of the flanks of the liner has formed a recess therein, and a securing pin is screwed into the holder portion adjacent to this flank and projects into the recess for securing the liner against lengthwise displacement in the groove of the holder.

BRIEF DESCRIPTION OF THE DRAWINGS A preferred embodiment of a clamping holder for a cutting tool according to the invention will now be described in detail, by way of example, with reference to the accompanying drawings in which FIG. 1 is a lateral elevation of the clamping holder;

FIG. 2 is a vertical section along line II-II in FIG. 1; and;

FIG. 3 is a vertical section along line Ill-III in FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT The tool holder 1 shown in FIGS. 1 to 3 comprises an elongated groove 2 of dovetailed cross-section wherein a clamping liner 3 is placed with transversal play. It is best seen in FIG. 3 that this liner 3 has a U-shaped cross-section with two wedge-like flanks 4 the outer surface 5 of which is parallel to the one respectively the other of the longitudinal lateral surfaces 6 of the dovetailed groove 2. The square steel bar 7 of a cutting tool 8, such as a lathe tool, is embraced on three longitudinal sides by the liner 3, whereby the inner surface 9 of its two flanks 4 substantially abut each against one of two opposite longitudinal sides of the tool bar 7. The middle wall 10 of the liner 3, which connects the flanks 4 is located near the longitudinal opening of the groove 2 and is traversed by two headless pressing screws 11 screwed therein and having a hexagonal hole 12 in the outer front end.

When the screws 11 are screwed in by means of a hexagon spanner to be inserted into the hole 12 their inner front ends will press upon the longitudinal side of the tool bar 7, which faces the middle wall 10, and will urge the tool bar with its opposite longitudinal side upon the base surface 13 of the groove 2 and the liner 3 by its outer flank surface 5 against the lateral groove surfaces 6. Thereby the wedge action of the flanks 4 produces from opposite sides a clamping pressure by way of their surfaces 9 upon the longitudinal sides of the tool bar which face the flanks 4, so that on the whole the tool bar is clamped in the holder 1 on all four longitudinal sides.

In order to prevent lengthwise displacement of the liner 3 in loose condition along the groove 2, a securing pin 14 is screwed through a holder portion being adjacent to one of the flanks 4 of the liner and projects with its inner end 15 into a recess provided in this flank.

What I claim is:

1. A clamping holder for a cutting tool, comprising a holder body provided with an elongated groove of dovetailed cross-section for lengthwise accommodation of the square steel bar of the cutting tool to be clamped therein, a wedge-like liner of U-shaped crosssection placed with transversal play in said groove and adapted to embrace the tool bar on three longitudinal sides, said liner having two flanks withan outer wedge surface on opposite sides longitudinally to said groove and a middle wall connecting said flanks and being located near the longitudinal opening of said groove, one of said flanks of said liner formed with a recess therein, a securing pin screwed into said holder body adjacent to said flank and projecting into said recess for securing said liner against lengthwise displacement in said groove of said holder body and pressing screws screwed through said middle wall for engaging the middle of the embraced sides of the tool bar and for urging the latter with its opposite side into clamping engagement with the base surface of said groove, whereby said flanks of said liner are under wedge action by said holder body and thus adapted to press upon the two other longitudinal sides of the tool bar. 

1. A clamping holder for a cutting tool, comprising a holder body provided with an elongated groove of dovetailed crosssection for lengthwise accommodation of the square steel bar of the cutting tool to be clamped therein, a wedge-like liner of Ushaped cross-section placed with transversal play in said groove and adapted to embrace the tool bar on three longitudinal sides, said liner having two flanks with an outer wedge surface on opposite sides longitudinally to said groove and a middle wall connecting said flanks and being located near the longitudinal opening of said groove, one of said flanks of said liner formed with a recess therein, a securing pin screwed into said holder body adjacent to said flank and projecting into said recess for securing said liner against lengthwise displacement in said groove of said holder body and pressing screws screwed through said middle wall for engaging the middle of the embraced sides of the tool bar and for urging the latter with its opposite side into clamping engagement with the base surface of said groove, whereby said flanks of said liner are under wedge action by said holder body and thus adapted to press upon the two other longitudinal sides of the tool bar. 